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The project is a major renovation for a data center in an existing industrial park. The existing front parking area has an abundance of tree growth that effectively provides a cutoff of illumination g...

Inquiry

The project is a major renovation for a data center in an existing industrial park. The existing front parking area has an abundance of tree growth that effectively provides a cutoff of illumination generated from the pole mounted 250W HPS fixtures. The fixture is a cutoff type as required by the credit. Will it be acceptable to observe/record lighting levels at the property line in lieu of calculations? Any illumination calculations will not model tree growth and will show lighting to be non-conforming to the credit. But if we can submit recorded/observed lighting levels it is likely we will comply with the .2fc max.

Ruling

The project team has asked if field measurements can be used instead of a computer simulation given that they cannot simulate the landscaping and the landscaping provides shielding.. No, field measurements are not acceptable because landscape and trees will grow or may be cut down, trimmed or changed in the future. Deciduous trees will lose their leaves for part of the year and provide a much lower shielding effect. Furthermore, the health of some species of trees may be negatively impacted by nighttime lighting. A lighting solution, based on a computer simulation without trees, that better controls the light to limit it at the tree line represents a strategy more in line with the intent of the light pollution credit. This may be accomplished with luminaire optics with a shorter "forward throw" or a lower wattage lamp. Applicable Internationally.

Because the criteria for Sustainable Sites Credit 8 have changed substantially from LEED-NC version 2.1 and version 2.2, this Credit Interpretation Request seeks guidance on whether CIRs issued for v2...

Inquiry

Because the criteria for Sustainable Sites Credit 8 have changed substantially from LEED-NC version 2.1 and version 2.2, this Credit Interpretation Request seeks guidance on whether CIRs issued for v2.1 would apply to similar situations under v2.2. The Tacoma Center for Urban Waters (TCUW) is a new 56,000 square foot office and laboratory building, located on the east side of the Thea Foss waterway in an area currently occupied by industrial uses. The ambient light level of this area is not high due to the fact that very little night use occurs. The TCUW will include facilities that are available to community groups and it is anticipated that a fair amount of after-hours use will take place. In addition, security for TCUW staff is a concern even during normal operating hours, as the Tacoma area experiences very short days during the winter months and it is anticipated that staff will arrive and leave in darkness for a significant part of the year. We have determined that the site qualifies as LZ3 - Medium (Commercial/Industrial, High-Density Residential) based on the current use of the surrounding area as well as the proposed use by TCUW. We would like to confirm that uplights which are shielded (i.e., located under an opaque canopy) would not count toward the percentage of allowable uplight under v2.2. We would also like to confirm that the principle outlined in the Columbia Heights CIR (12/1/2006) would apply to the TCUW project. The project includes a portion of the building that is set back from the property line by only 5 feet. The adjacent property is a narrow strip between our project and the city street that is used to park tanker trucks for the adjacent industrial uses. Our lighting of this area addresses two concerns. The first is security in this area, which does not receive any significant ambient lighting from surrounding properties or the street. Because views to the street are often blocked by parked trucks, the feeling of security in this area is very important. Also, the entire area between the building and the property line contains a sidewalk which also serves as path of egress to the public way. Our lighting scheme provides a maximum of 0.61 footcandles (fc) of horizontal illuminance and 1.0 fc of vertical illumination at the property line, which is also the curb line of the sidewalk. However, at 10 feet beyond the property line, light levels are 0.01 fc, with 0 fc at 15 feet beyond the property line. We have achieved this by utilizing a low-wattage (13 watt), wide-distribution fluorescent source, mounted at a low height (3.5 feet) on the building wall that adjoins the sidewalk. This fixture emits all light at angles below 90 degrees. All other components of the project comply with this credit, and we would like to confirm that our approach regarding the egress path lighting meets LEED's intent to reduce light pollution while allowing the project to meet code and security requirements.

Ruling

1. Uplighting under an opaque canopy If the uplight is COMPLETELY contained under an opaque canopy, it does not have to be considered in the uplight tabulation. To document this, the team must show that a) the canopy is indeed completely opaque and b) that all angles where a candela value is emitted from the luminaire are blocked by the canopy. Provide a specification for the canopy material and a line diagram showing the canopy/luminaire geometry. If the luminaire is adjustable, the team must show that it will be locked in position or that the canopy will block the light at all possible aiming angles. 2. Egress Lighting The team's proposal of using very a low wattage fluorescent lamp in a fully shielded luminaire will meet the intent of the credit while still providing the egress light necessary to meet code. Applicable Internationally.

The Argiro Student Center project has chosen to address one of the criteria in the Light Pollution Reduction credit in a way that differs from the strategies in the LEED-NC Manual. We have chosen to o...

Inquiry

The Argiro Student Center project has chosen to address one of the criteria in the Light Pollution Reduction credit in a way that differs from the strategies in the LEED-NC Manual. We have chosen to officially establish that the full time janitorial staff, who go into the building for routine cleaning purposes at night, ensure, as part of their necessary responsibilities, that all lights are turned off after hours. This strategy should effectively eliminate undue light trespass from the building in the evening hours and, thereby, this strategy should adequately fulfill the intention of the "minimize light trespass from the building" aspect of the Light Pollution Reduction credit. This compliance route may take the place of the suggestion that: "all non-emergency interior lighting shall be automatically controlled to turn off during non-business hours." The project has chosen alternative compliance for the first part of this credit. And the project intends to fulfill the requirements for exterior lighting as listed in the manual. If the USGBC accepts our alternative compliance route then we may plan to receive a credit for our work in this category.

Ruling

The team proposed an alternate compliance path where the custodial staff would turn off the interior lights at night to minimize light spill and trespass. This does not qualify as an approved compliance path for the following reasons:

ASHRAE requires a certain level of nighttime lighting control to turn off all unnecessary lighting. Therefore, lighting control needs to be implemented anyway to meet these energy requirements.

Custodial staff may change and should not be relied upon to keep all lighting off.

Our current project is approximately a 75,000 sf student dormitory. The alternate compliance path (Option 2)states that light fixtures are to be automatically controlled and programmed to turn off fol...

Inquiry

Our current project is approximately a 75,000 sf student dormitory. The alternate compliance path (Option 2)states that light fixtures are to be automatically controlled and programmed to turn off following regular business hours. Since this a dormitory, regular business hours would not apply. The current design calls for digital timers and occupancy sensors in spaces accessible to students which include lounges, studies, corridors, and trash rooms. Digital timers have a on/off manual override, and the occ sensors have a switch upstream for manual override off, occ sensor on. Additionally, each floor will have a RA for "lights out." Please indicate if the current design scope would comply with Option 2 with these considerations.

Ruling

The Approach and Implementation section of the SSc8 Reference Guide credit description allows for the following lighting control strategies to meet the intent of the second compliance path: "Controls may be automatic sweep timers, occupancy sensors, or programmed master lighting control panels. Manual override capabilities that enable lights to be turned on for after-hours use must be included in the design." As described, the lighting control for student accessible spaces sounds appropriate, as it is based on occupancy sensors with over-ride switches. Obviously in a dormitory setting there is a certain baseline-level amount of lighting that is required at all times for security purposes. If a light fixture is to remain on through the entire night, it should meet the requirements of the first compliance path, namely the angle of maximum candela should not pass through transparent or translucent building surfaces. Defensible exceptions can be made at entrances and exits to the building where required for safety. Please note that you would also have to address credit compliance for those spaces that have not been mentioned in this CIR (such as areas off-limits to students, which do not require 24 hour lighting). Applicable Internationally.

The project is a four level public parking ramp that is an independent building from but serves several floors of condominiums and a 24 hour operated casino, which makes the parking ramp a 24 hour occ...

Inquiry

The project is a four level public parking ramp that is an independent building from but serves several floors of condominiums and a 24 hour operated casino, which makes the parking ramp a 24 hour occupied structure. There are no exterior walls on the ramp with the exception of floor to ceiling structural columns on a 24' by 56' grid. The fixtures are mounted at 11' above the finished floor and placed within 10' of the edge of the decks with a glare shield to reduce light spill out from the ramp. The LEED interior lighting requirements state that "The angle of maximum candela for each interior luminaire as located in the building shall intersect opaque building interior surfaces and not exit out through the windows." We have no windows on the parking structure and no other way to prevent light from escaping from the structure on the sides where it does not directly abut another building. We are asking for an interpretation as to whether this is considered an interior or an exterior lighting application? A ruling will help us determine if we will be able to pursue a LEED credit for light pollution reduction on this project.

Ruling

The applicant is seeking clarification as to the interior/exterior area classification for a four level open air parking ramp building. For the purposes of SSc8, parking structure covered floor area is to be considered interior area and uncovered area is to be considered exterior area. Thus, any lighting within covered area must meet the interior lighting requirements of this credit and any lighting within uncovered area must meet the exterior lighting requirements of this credit, including being below specified foot candles horizontal and vertical at all locations outside the boundary of the property. For the purposes of clarity, the credit requirements pertaining to interior luminaires' angle of maximum candela not exiting out windows also requires that interior luminaires' angle of maximum candela not exit out building openings or other translucent surfaces. Applicable Internationally.

Inquiry

Our project is a 238,000 SF brick manufacturing facility in Terre Haute, Indiana. The project consists of 5,000 SF of office space and 233,000 SF of manufacturing area, including extrusion, drying, and kiln equipment. The requirement for INTERIOR LIGHTING indicates "The angle of maximum candela from each interior luminaire as located in the building shall intersect opaque building interior surfaces and not exit out through the windows." This would indicate that light other than that emitted by the angle of maximum candela would be allowed to exit thru non-opaque surfaces. Our building design includes diffuse translucent panels along the perimeter walls which allow 40% transmission of light through them. The angle of maximum candela does intersect these translucent surfaces, but the light is diffused by the panels. Even at the angle of maximum candela, any interior light passing through to the exterior is substantially reduced. Please verify that this meets the intent of the credit by minimizing light trespass from the building.

Ruling

The project, as described, does not meet the full requirements of the credit. The applicant has quoted the requirements from the initial credit description, but more detailed requirements are laid out in the Approach and Implementation section of the LEED-NC v2.2 Reference Guide SSc8 description, including "preventing light spill through transparent and translucent surfaces to exterior areas" and to "confirm that the maximum candela angle does not intersect transparent or translucent building surfaces that face exterior areas." If it is not possible to alter the building design to meet the requirements described above, it is still possible to achieve the credit using the alternate compliance path presented in "Option 2" of the Interior Building Lighting section in the Reference Guide.

Inquiry

Our project is a 238,000 SF brick manufacturing facility in Terre Haute, Indiana. The project consists of 5,000 SF of office space and 233,000 SF of manufacturing area, including extrusion, drying, and kiln equipment. The requirement for INTERIOR LIGHTING indicates "The angle of maximum candela from each interior luminaire as located in the building shall intersect opaque building interior surfaces and not exit out through the windows." This would indicate that light other than that emitted by the angle of maximum candela would be allowed to exit thru non-opaque surfaces. Our building design includes diffuse translucent panels along the perimeter walls which allow 40% transmission of light through them. The angle of maximum candela does intersect these translucent surfaces, but the light is diffused by the panels. Even at the angle of maximum candela, any interior light passing through to the exterior is substantially reduced. Please verify that this meets the intent of the credit by minimizing light trespass from the building.

Ruling

The project, as described, does not meet the full requirements of the credit. The applicant has quoted the requirements from the initial credit description, but more detailed requirements are laid out in the Approach and Implementation section of the LEED-NC v2.2 Reference Guide SSc8 description, including "preventing light spill through transparent and translucent surfaces to exterior areas" and to "confirm that the maximum candela angle does not intersect transparent or translucent building surfaces that face exterior areas." If it is not possible to alter the building design to meet the requirements described above, it is still possible to achieve the credit using the alternate compliance path presented in "Option 2" of the Interior Building Lighting section in the Reference Guide. Applicable internationally.

The project is a four-story, 60,000 SF, speculative office building that is being submitted under LEED-CS. As we understand the intent, Credit SS8 - Light Pollution Reduction, aims to reduce light pol...

Inquiry

The project is a four-story, 60,000 SF, speculative office building that is being submitted under LEED-CS. As we understand the intent, Credit SS8 - Light Pollution Reduction, aims to reduce light pollution through the control of interior lighting, exterior light distribution, and exterior lighting power density. Our question concerns the calculation requirements for the exterior lighting power density. We have been very diligent about reducing the overall lighting power density across the site. The site lighting has a 47% reduction of light power density as compared with the allowable light power density in ASHRAE 90.1.2004. All of our exterior site lighting is on a photocell/master time control system that turns off all non-emergency lights at 10pm. Because of the neighboring uses, we have voluntarily eliminated all building façade lighting on the western façade, which accounts for nearly a third of the total building façade. This allows us to focus our façade lighting on the public face of the building, adjacent to walkways, parking, etc.. Based on our total façade area (including the western façade) our lighting power density meets the credit requirement of 0.1 watts/SF. ASHRAE, however, calculates the LPD for each illuminated façade. Using this methodology, our LPD is 0.16 watts/SF, which is a 20% reduction from the ASHRAE standard. Does this meet the intent of the credit?

Ruling

The CIR is inquiring if projects can combine the lighting power densities for all building façade lighting when calculating compliance for this credit. Per the referenced ASHRAE Standard, building façades must be calculated individually and are considered non-tradable (cannot be traded between surfaces or with other exterior lighting areas.) In order to demonstrate compliance with the requirements of this credit, projects must document a minimum 50% LPD reduction from the ASHRAE Standard Allowable LPD for building façade and landscape lighting for each individual illuminated façade. Additionally, the intent of the credit is to minimize the amount and overall intensity of installed site lighting to increase night sky access. Increasing the lighting intensity on one façade above the minimum requirements, although other facades are non-illuminated does not meet the intent of this credit. Applicable Internationally.

Inquiry

SUSTAINABLE SITES: Light Pollution Reduction (SSc80) Credit Interpretation Request (Registered under NC 2.1 but submitting this credit under NC 2.2 through LEED Online) Our project is the new construction of a 47,000 ft2 4-story recreation/office building to serve as a community center for the Washington, DC Parks and Recreation Department. The program consists of an indoor gymnasium and stage, multipurpose room, offices, classrooms, weight and exercise room, and locker room facilities. The property sits at the intersection of two streets in the Columbia Heights neighborhood, and the building hugs the property line so that there is a "zero-property line" condition along the street corner. Across the street to the north of the property are high-density residential properties and across the street to the west are diplomatic buildings. To the east of our site boundary is a park with a playground and basketball court owned by DC Parks and Recreation. The southern boundary is bounded by a multi level apartment. The city street lights along the block are cobraheads, so there is significant ambient lighting. These are pre-existing fixtures that are not part of the scope of this project. We have determined that the site qualifies as LZ3 - Medium (Commercial/Industrial, High-Density Residential) Environmental Zone. We are requesting an interpretation for the requirement to design exterior lighting so that all site and building mounted luminaires produce a maximum initial illuminance value no greater than 0.20 horizontal and vertical footcandles at the site boundary or in this case the curbline, and no greater than 0.01 horizontal footcandles 15 feet beyond the site. Our lighting design currently meets all other requirements of this credit. However, there are 2 areas on the north side of the site where the horizontal and vertical illuminance values are between 0.20 and 0.30 for about 10 feet along the curb line that meets public streets, but they do drop to less than 0.01 footcandles 15feet beyond the curb line. These areas correspond to locations where exit doors exist. In these locations, fixtures are being provided to meet illumination requirements set forth by the National Fire Protection Association (NFPA) code NFPA 101 - Life Safety Code Chapter 7 for means of egress. Their requirement is to provide a minimum illumination on walking surfaces of 1 footcandle for exit passageways leading to a public way. The fixture being used is a wide throw fixture with a 26 watt compact fluorescent lamp that produces 1800 initial total lumens all emitted at an angle less than 90 degrees. These fixtures illuminate the side walk to the required 1 footcandle. The curb line for the street that is well lit by cobraheads is only 3.5ft from the sidewalk. Thus, the 0.30 footcandles at the curb line will be nothing in comparison to the light emitted by the streetlights. Illuminating Engineering Society of North America (IESNA) RP-33-99 describes light trespass to fit into one of two categories: - Adjacent property receives unwanted light (high illuminance levels) - Excessive brightness occurs in the normal field of vision (nuisance glare) In this case we believe that neither of these conditions exists. Do you agree that this design meets LEED's intent to reduce light pollution by minimizing light trespass while still upholding current design practices and meeting code requirements?

Ruling

The proposed strategy for meeting the intent of the credit is acceptable given the context and adjacencies of your project. Two spaces are slightly over the maximum illuminance values at the site boundary, but these spaces are incompliance at 15 feet beyond the boundary. Given the other lighting adjacencies in those areas and the fact that the project complies with all other criteria, the intent of the credit is being met.

The credit guidelines to limit light trespass created by the building and site lighting being confined to the property is appropriate for most situations, but is incompatible with the requirements of...

Inquiry

The credit guidelines to limit light trespass created by the building and site lighting being confined to the property is appropriate for most situations, but is incompatible with the requirements of transitional traffic zones that enter and exit the property and therefore generally located on the property line for most applications. The lighting provided at the property line for road entrance and exit locations serves a variety of purposes, namely: 1. The property area for the road crossing location is an area of potential pedestrian-vehicle conflict. This area requires an appropriate level of illumination for the safety of the pedestrians and for clear visibility of vehicle operators. 2. The area in question is an intersection. Illuminating Engineering Society of North America (IESNA) RP 8 (Standard Practice for Roadway Lighting) recommends that the illumination levels at vehicle conflict locations be increased above similar recommended roadway lighting levels. 3. Vehicle traffic will require a minimal amount of transitional lighting when leaving or entering a lit roadway. Variations in illumination have detrimental effects to the driver that increase the potential for an accident. 4. Provides awareness of vehicle traffic outside of the property to potential inflow of new vehicles. The particular application of this credit interpretation concerns a hospital emergency centre located in a downtown area with high traffic and pedestrian volumes. The site includes a surface parking area for emergency response and public vehicle traffic responding to the emergency centre. Individuals entering the property will often be unfamiliar with the environment and will therefore require a degree of illumination that promotes an awareness of the surroundings allowing them to safely navigate the area. The lighting design for the facility takes into consideration recommended practices outlined in the LEED credit for reducing light pollution. All exterior luminaires are provided as full cut-off type with internal source shielding ensuring no direct illumination is provided above the horizontal plane to limit any spill lighting. With the exception of traffic conflict areas, the exterior lighting design has confined all illumination within the property boundaries. IESNA RP 8 item 3.6.2 states ".driveways serving high volume activities.should be illuminated similar to a major/major intersection." Item 3.6.4 states ".traffic conflict areas should be provided with illuminance values 50 percent higher than recommended for the street." Surrounding roadways would be classified as "collector" routes with "high" degrees of potential pedestrian conflict locations. Table 9 of IESNA RP 8 suggests that the average maintained illumination at the pavement level for this type of intersection be provided with 24.0/2.4 (lux/fc). This is significantly higher than the 6.0/0.6 (lux/fc) level requirement of LEED. The Lake Union District CIR (08/16/2003) addresses spill lighting from the property, but not specifically with respect to traffic intersection. The lighting levels provided at the traffic intersections located for our project design are provided more closely in compliance with IESNA RP 8 for recommended lighting levels at the traffic boundary locations. For our application, the spill lighting will be provided onto a roadway and no lighting will penetrate adjacent property windows. The levels dictated however are inadequate for the recommended lighting requirements of this application. For pedestrian safety, it is imperative to provide an appropriate level of illumination that meets the requirements of all involved. Without a re-evaluation of the lighting requirements of this credit, it will not be possible to provide for the recommended practice lighting levels for most projects at traffic congestion locations. It is requested that the LEED credit requirements allowing no light trespass at the property line be relaxed at traffic conflict locations and be more closely defined so as to allow the designer the ability to provide the appropriate lighting levels for these locations while meeting the intent of the credit.

Ruling

The Lake Union District CIR (8/16/2003) was intended to light alleyways, not streets, and is not appropriate for this CIR. Because this site abuts a public right of way, the 6 lux (0.6 fc) requirement may be met relative to the curb line instead of the site boundary, and drop to 0.01 fc (0.1 lux) 15 feet past the curb line per LEED v2.2 SSc8 requirements. The determination of the lighting zone takes into account the nature of surrounding properties and sets the light trespass limit given the overall ambient brightness.

***Update 1/1/13: LI 1622 has been superseded by LI 10236. 1622 is no longer valid.

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